Oxidation-stable developer compositions



r h 3,050,392 Ice Patented Aug- 1962 3,050,392 OXIDATION-STAELEDEVELOPER CQMPOSITIONS John Eerde, New York, N.Y., assignor toMergenthaler Linotype Company, a corporation of New York No Drawing.Filed Aug. 1, 1958, Ser. No. 752,441 9 Claims. (Cl. 96-61) Thisinvention relates to photographic developers, and more particularly tophotographic developers possessing improved stability to aerialoxidation.

The most common developers used in photography are alkaline solutions oforganic reducing agents capable of reducing exposed silver halideemulsion grains to metallic silver in proportion to their exposure tolight. These organic developing agents are primarily di-hydroxy,diamino, or amino-hydroxy substitution products of benzene such asglycin or hydroquinone, the sulphate of paramethyl aminophenol,1,2,3-tri hydroxy benzene, etc. It is common practice to accelerate theslow reducing action of these developing agents to a range of practicalactivity by using them in an alkaline medium which in turn makes themsubject to rapid aerial oxidation. Furthermore, it is common practice touse these alkaline developers in the presence of sodium sulfite which iscapable of retarding the rate of aerial oxidation. Developing agents,once oxidized, lose their ability of reducing the silver salts tometallic silver, i.e., of developing an image.

Occasionally, developers are exhausted by processing a large quantity offilm or paper continually within a short period of time. In thisinstance the rate of aerial oxidation may not be significant. However,and more often in practice, developers are used only periodically over arelatively long period of time. In this instance, and particularly inthe case when airtight storage of used developers between processingperiods is not feasible, aerial oxidation destroys the developer longbefore its processing capacity has been utilized.

In the fields of professional and technical photography it is notdesirable to adjust (i.e. increase) exposures in order to obtainconsistent and reproducible film or print densities, thus compensatingfor the gradual, or in some instances sudden, decline of developingpower of a given developer formula due to oxidation.

1 have discovered that the addition of an alkali metal arsenite to asulfite containing developer will substantially increase theoxidation-stable characteristics of such a developer.

Improvement of the oxidation-resistance of sulfite containing developersis therefore an objective of the present invention, which provides ameans of extending the useful life of developers.

By means of the addition of an alkali metal arsenite, the useful life ofsulfite containing developers has been greatly extended. The resultshave been startlingly good, and could not possibly have been predictedbeforehand. In fact the prior art suggests that arsenites would beineffective. For example, Crabtree and Schwingel, in the Journal of theSociety of Motion Picture Engineers for April 1940, state at page 389that when a portion of the sodium sulfite in a developer was replaced byequivalent quantities of sodium arsenite and sodium hypophosphite, noimprovement Was noted. The probable explanation for the results ofCrabtree et a1. is that they substituted arsenite for sulfite. In thepresent invention, arsenite is When Crabtree altered the sulfiteconcentration, he also admittedly altered the respective sensitometriccharacteristics of the developer, and the arsenite could not undo thedamage. In the present invention, the amount of sulfite is not altered.Alkali metal arsenite is added to the developer, and not used as asubstitute for sulfite in the formula.

To determine the efiectiveness of arsenite addition as a means ofimproved resistance to aerial oxidation of sulfite containingdevelopers, I have used the following test procedure.

Essentially, I have exposed identical developer compositions, with andwithout the addition of an arsenite salt to aerial oxidation inpartially filled jars. At the start of this shelf aging period, andafter certain intervals, I have developed film in these partially filledjars under carefully controlled conditions and compared the resultingdensities of both the unprotected and protected developer compositions.Specifically, I have employed wide mouthed clear glass jars with 1000ml. capacity which were charged with ml., or 50 ml. of developersolutions.

At the start of the shelf aging test period, the arsenite salt was addedto the coded jar, leaving the unprotected identical developercomposition in the control jar. A sheet film of the appropriatedeveloper-film emulsion combination was exposed behind a step wedgeunder standardized conditions, and developed in the jar containing theaged developer using reproducible mechanical agitation. chosen to leavea substantial column of air in the jar to react With the developer andso hasten its breakdown due to aerial oxidation. To minimize fluid lossdue to evaporation, the mouth of each jar was covered during theshelf-aging periods. Periodically, however, each jar was uncovered for afixed period to replace atmospheric oxygen consumed in the jars duringthe storage periods. At given intervals film was processed in the jarsand evaluated by-recording the resulting maximum density as measured byan Ansco Sweet Color Densitometer, Mod. 12.

The developers used in the following examples are representative of thecommonly used types of developers. In the case of the developers knownas ID35, D-19, D-72, D-SS, 61-D, 1-D and A.B.C. pyro-soda, thecompositions used in the examples were made up according to thedirections published in the literature for'the developers known by thosenames.

In general the optimum amount of arsenite to be added varies with thecomposition of a developer. Concentrations as low as 0.05% have producedimprovement in some cases, and so have concentrations as high as 30%. Ingeneral, however, the optimum concentration of the alkali metal arsenitein the developer solution is in the range of from about 1% to about 10%.

Sulfite containing developers are usually alkaline. When the developeris alkaline, the alkakli metal arsenite can be formed in situ by theaddition of arsenic trioxide.

The following examples are given solely for purposes of illustration andare not to be considered as limiting the invention to these embodiments.Many modifications will be apparent to those skilled in the art withoutdepart EXAMPLE I Object: To determine the stabilizing or protectiveaction of NaA'sO in a high contrast type developer suitable forphoto-mechanical work and reversal processing of high contrastemulsions.

The small volume of developer solution was Formula ML-4 Part A:

Water ml 375.0 Sodium sulfite, anhydrous grams 15.0 Hydroquinone do 22.5Acid sulfuric C.P do 2.0 l-phenyl 3-pyrazolidone do 0.2 Water to make500 ml.

Part B:

Water ml 375.0 Sodium sulfite, anhydrous grams 45 .0 Sodium carbonate,monohydrated do 17.5 Potassium carbonate do 45 .0 Potassium bromide do4.15 Benzotriazole in 10 ml. ethyl alcohol do 0.2 Water to make 500 m1.

For use take equal parts of Part A and Part B. The pH of the workingsolution is 10.3. As is apparent Part A contains essentially thedeveloping agents, and Part B contains essentially the alkaliaccelerators. The arsenite salt was added to Part B at the start of theaging test. Kodalith Ortho Type 2 sheet film was processed in accordancewith the previously described method; the following table records themaximum densities obtained using at all times an exposure of 4 secondsand a developing time of 135 seconds. The temperature of the developerswas adjusted at all times to 69 Ril F.

Addition Maximum Maximum density after of NaAs density shelf agingDeveloper formula 100 ml. of at start developer, of shelf g. aging 520hrs. 828 hrs.

ML-4 0. 00 4. 68 1.72 No image MIr-i 3. 80 1 3. 98 3. 64 3.01

1 Initial depression of density due to addition of NaAsOz.

These data illustrate the pronounced retarding action NaAsO on thedeterioration of the developer, i.e., a substantial extension of theuseful life of the developer subjected to aerial oxidation. Thefollowing table illustrates how the optimum concentration of NaAsO inthe ML4 developer was arrived at.

Addition of Maximum N aAsOg/IOO density Developer formula ml. ofMolarlty at start or developer, shelf aging HOURS 1 No image (zerodensity).

EXAMPLE I1 Object: To determine the stabilizing action of NaAsO- in adeveloper designed for photo-mechanical work (process photography).

Formula ID-35 Stock solution A:

Water (125 F.) ml 750.0 Hydroquinone ..grams 37.5 Sodium sulfite,desiccated do 94.0 Potassium bromide do 9.0

Water to make 1000 ml.

4 Stock solution B:

Sodium carbonate, monohydrated grams 217 Water to make 1000.0 ml.

For use, take equal parts of A and B. The pH of the working solution is11.0.

Kodalith Ortho Type 2 sheet film was exposed behind a step wedge for 2/2 seconds and developed for 5 minutes at 69 F using constant mechanicalagitation.

The following table records the maximum densities obtained after anaeration period of /2 hours.

Object: To determine the stabilizing action of NaAsO in a normal to highcontrast type developer which is identified as a long-life, non-stainingtray developer, causing very little chemical fog. This developer wasoriginally designed as an X-ray developer but is also recommended forthe development of aerial films, and for films and plates when it isdesirable to obtain high contrast With a short developing time.

Formula D] 9 Water ml 500 Elon (monomethyl para aminophenol sulfate)"grams" 2.2 Sodium sulfite, desiccated do 96.0 Hydroquinone do 8.8Sodium carbonate, monohydrated do 56.0 Potassium bromide do 5.0

Water to make 1000.0 ml. The pH of the working solution is 11.0.

Addition Maximum Maximum Density after Developer formula ofNaAsOi/density at shelf aging ml. destart of veloper, g. shelf aging 168 hrs.192 hrs.

Dl9 0.00 4. 73 0.09 1 No image 1. 0 4. 58 3. 30 2. 45

1 Zero film density.

Kodalith Ortho Type 2 sheet film was exposed behind a step wedge for 4seconds and developed for 2% minutes with constant mechanical agitation.Developer temperature was adjusted to 69. F.i 1 F.

EXAMPLE IV Object: To determine the stabilizing action of NaAsO in aUniversal type developer.

Formula D-72 Water .ml 500 Elon (monomethyl para aminophenol sulfate)grams 3.1 Sodium sulfite, desiccated do.. 45.0 Hydroquinone do.. 12.0Sodium carbonate, monohydrated do 80.0 Potassium bromide do 1.9 Water tomake 1000.0 ml.

The developer was used undiluted. Kodalith Ortho Type 2 sheet film wasexposed behind a step wedge for 4 seconds and developed for 5 minuteswith constant mechanical agitation.

The pH of the solution (D-72) undiluted is 11.0 and in the customary 1:2dilution the pH is 10.9.

Addition Maximum Maximum density after i of NaAs density shelf agingDeveloper formula 100 ml. deat start veloper, g. of shelf aging 312 hrs.364 hrs.

EXAMPLE V Formula D-85 Water ml 500 Sodium sulfite, desiccated grams 30Paraformaldehyde do 7.5 Sodium bisulfite do 2.2 Boric acid, crystals do7.5 Hydroquinone do 22.5 Potassium bromide do 1.6

Water to make 1000 ml. The solution has a pH of 10.5.

Addition Maximum Maximum density after of N aAsO z/ density shelf agingDeveloper 100 ml. deat start formula veloper, g. of shelf aging 3 hrs.5% hrs. 7 hrs.

D-85 0. O0 3. 84 3. 40 0. 20 1 N0 image D-85 8 0 3.82 3.81 3.00 2.82

1 Zero film density.

The volume of test solution was 100 ml.

EXAMPLE VI Object: To determine the oxidation retarding, i.e.,stabilizing effect of NaAsO in an Amidol (diaminophenoldi-hydro-chloride) developer. Such developers are preferentially used aspaper developers due to their ability of producing an excellent silverdeposit of a blue-black color and quite satisfactory tonal value.However, due to the extremely high reduction potential of the Amidol(3040 vs. 1 of hydroquinone, for example) the developer is considerednot too stable in comparison with a Metolhydroquinone developer (such asD72) in spite of the fact that there is no carbonate or other alkalipresent.

The paper used was Varigam, a multiple contrast paper, having projectionspeed characteristics. Filter selection and exposure were determined bythe requirement of obtaining an optimum gradation, i.e., best possiblereproduction of the step wedge. Development, carried out in trays, wasfor 4 minutes at 70 F. and with constant manual agitation. 150 ml. ofdeveloper solutions were aged in 1 quart capacity jars.

Formula 61-D Water ml 750 Sodium sulfite, desiccated grams 15.4 Amidoldo 3.8 Potassium bromide do 2.5

Water to make 1000.0 ml. The pH of this solution is 7.0.

This Amidol developer formula shows very rapid deterioration ofdeveloping powers in a pronounced alkaline or acid medium. The sodiumarsenite addition shifted Maximum density after shelf aging AdditionMaximum of NaAsO density 100 m1. deat start veloper, g. of shelf agingDeveloper formula 25% hrs. 45 hrs.

til-D 1 Measured with the reflection head of the densitometer.

EXAMPLE VII Object: To determine the stabilizing effect of NaAsO in arepresentative one-bath deve1oper-fixer (monobath).

Such solutions, when used for fixing and developing accomplish both thedeveloping and fixing in a single operation. It is not necessary toremove the film or paper promptly after developing and fixing, becauseover-development cannot take place.

The processing kinetics are achieved by adjusting the concentration ofthe developing and fixing components in the single solution in such amanner that the reaction rate of the developing process proceeds at sucha rate that it is practically finished by the time fixing action gainsmomentum. The necessarily high velocity of the developing process isobtained by a high concentration of alkaline acceleration which, inturn, make such formulas especially prone to aerial oxidation. Thebalance between developer activity and fixing rate must be adjusted tofit specific emulsion characteristics.

Scientific and patent literature make reference to various methods ofcombined developer-fixers. U.S. Patent 2,138,486 granted to ErnestFournes and myself describes oxidation-stable her-developers which maybe used over a relatively long period of time with reasonably goodresults.

The solutions of that patent contain an organic developing agent, afixing agent, a caustic alkali and a reducing carbohydrate, theinvention consisting in the use, along with the caustic alkali, of thereducing carbohydrate which renders the solutions stable.

The solutions of said Patent 2,138,486 while satisfactoryv for manypurposes, have, in use, certain disadvantages. For example, when freshlyprepared they give a degree of development different from that of asolution which has been used over a period of time, i.e., in which someof the active ingredients have been consumed. In addition, the obviousdisadvantages of working withcaustic alkalies are present, as well asthe fact that with certain emulsions such formulas produce relativelycoarse grain, causing lack of resolution or fine image detail.

The use of an alkali metal arsenite in conjunction with alkaline salts,such as sodium carbonate, trisodium phosphate, bonax, etc. enlarges therange over which the formulation of fixer-developers can be carried out,i.e., low to high gamma characteristics, etc. These solutions containingan arsenite as will be illustrated by the following table give an almostuniform degree of development during their entire life, hitherto notpossible in single solution developer-fixers.

Formula 74EM (monobath) Water ml 700 10% benzot-riazole in ethyl alcoholn11 10.0 Elon grams 6.0 Hydroquinone do 14.0 Sodium sulfite, desiccated;do 35.0 Sodium thiosulphate (N-a S O .5H O). do 40.0 Potassium bromidedo.. 6.0 Sodium phosphate, tribasic (Na PO .12I-I O) grams 45.0

Water to make 1000 ml. The pH of solution is 11.0.

Maximum density Shelf aging Formula periods hrs. 47 hrs. 69 hrs. 138.5

Control 2. 55 2. 40 2.30 l 1.12 74EM unprotected. 1% NaAsOg--. 2. 45 2.20 2. 04 1. 78 7413M protected. 4% NaAsOz.-- 2 2. 53 2 2. 60 I 2. 58 i2. 47 Do. 8% NaAsOz. 3. 02 2. 75 2. 70 1. 62 Do.

Brownish film stain (emulsion gelatin, due to oxidation products ofdeveloping agent).

Consistent reproducible developing characteristlcs.

EXAMPLE VIII Object: To determine the stabilizing effect of potassiumarsenite (KAsO in a representative pyrogal'lol developer. The formulachosen for evaluation is a standard A.B.C. pyrosoda developer for whichthe following characteristics are recorded. Working solutions for sheetfilm-s should be used only once since the developing agent (pyrogallol)oxidizes rapidly and repeated use of the developer produces negativeswith progressively darker pyro stain. Negatives of consistent qualityare produced only when fresh developer is used for each batch. Testprocedure:

Film-a medium panchromatic continuous tone emulsion (PanatomicX).

Exposure-2 /z seconds behind a #3 step wedge which has 21 steps on a /2transmittance scale. (This is equivalent to log E.0.3 increments.) A 32candle power, 6 volt lamp was used at a fixed distance from the printframe. To limit deterioration of the lamp filament, a rheostat was usedto reduce the applied line voltage. In addition, a current regulator wasused to prevent current fluctuations and finally, an electronic timerregulated the exposure duration.

Developmentminutes at 69 Ril" F. with constant mechanical agitationwhich was achieved by the transfer of the aging vessel, and after theinsertion of the exposed Panatornic-X film into a suitably designedlaboratory ball-mill.

Water to make 1000 ml.

Stock solution C:

Water ..ml 900 Sodium carbonate, monohydrated grams 88.0 Water to make1000 ml.

For use take:

1 part stock solution A 1 part stock solution B 1 part stock solution C7 parts water The pH of the working solution is 9.4.

Base densities are high due to stain caused by oxidation.

The test series recorded in the table demonstrates that the addition ofpotassium arseni-te to the pyrodeveloper has eliminated the pyro stain.

EXAMPLE IX Several test series were also conducted using preparedcommercial developers known to be particularly afiected by aerialoxidation.

To evaluate the effect on prolonging the useful life of a representativelitho developer by the simple addition of an alkaline oxidation-stablearsenite salt the following test was conducted.

Vivolith is a high energy, high contrast, lithographic type developer.It is known as an infectious developer. It contains bisulfite andformaldehyde. Vivolith is the trademark of Photochem Company, Inc.

Addition Maximum Maximum of N QASOQ/ density at I density Developerformula 100 ml. start of after 19 developer, shelf aging hours shelfaging Vivolith None 3. 49 0. 19 Do 10 3. 45 2.

EXAMPLE X Object: To determine the eifect of NaAsO in a high contrasttype developer (for photo-mechanical work) subjected to both aerationand exhaustion conditions. The formula used was ML-4. The film' wasKodalith Ortho Type 2, 4" X 5" sheet film which was exposed behind aKodak #3 step wedge for 4 seconds. The film was developed for 2%minutes; the developer temperature was adjusted to 69 F.

The solution volumes of both the unprotected control and the NaAsO-protected developer were ml. each at the start of the test. A total of50 4" X 5" sheet films were processed over a period of 12 days (289hours) at Which time the respective solution levels were down to 55 ml.At the beginning of the test single sheet films were developed at 30minute intervals (films #1#7), subsequently films were developed at 15minute intervals (films #18#42); finally, singles were processed todetect the first changes in developer characteristics.

Protected For- Tlme Unprotected mule ML-4, sequ nee of 4 5 1perioidfsFormula ML-4 N 3.25 grams e x e apse or aAsO 1 ml. sheet films developedshelf aging 2/ 00 film processing, hrs. Mar. Base Max. Base densitydensity Start 4. 91 0. 10 4. 09 0. 09 25% 4. 91 0. 09 4. 39 0. 09 97% 4.86 0. 09 4. 54 0. 09 100 4. G4 0. 09 4. 48 0. 09 104% 4. 38 0. 09 4. 400. 09 119 4. 13 0. O9 4. 20 0. 09 193 /4 2. 50 0.08 3. 91 0.08 9 1 2Zero 0.07 1 3 51 0.07 363 l 2 Zero 2 44 0.07 432 1 2 Zero 27 0. 06 482 19 Zero 28 0.05

1 Volume of respective developers 55 ml. 1 No image.

In the course of research on oxidation-stable developers it has beenfound that concentrations as low as 0.05 percent sodium arsenite showedmarked retardation of the developer breakdown due to atmospheric oxygen.Concentrations as high as 32.0 percent sodium arsenite in certainformulas gave a high degree of protection. Practical considerations,solubility, sediment formation after use, etc. made it desirable,however, to establish for each particular developer formula an optimumconcentration of the alkali metal arsenite.

Sodium sulfite, a compound present in practically all types of developerformulas, shows marked stability against atmospheric oxygen in thepresence of NaAsO In order to determine the stabilizing action of NaAsOon N21 50:, solutions a test series was carried out using oxygenation asa means of aging.

A percent Na SO solution after /4 hour oxygenation retained 26.8 percentof the original amount of Na SO By comparison, a 5 percent Na SOsolution to which were added 3.3 grams NaAsO 100 ml. retained after onehour 98.7% original Na SO and after 19 hours of oxygenation 27.5 percentof the original amount of Nazsoa.

The susceptibility of a developer to oxidation is dependent upon theinitial alkalinity of the solution, other components of the formularemaining constant, i.e., it depends upon the pH and not upon theparticular alkali employed. It is apparent that for a given developerthe rate of oxidation increases with increasing alkalinity.

It is known that in straight hydroquinone developers this rate is inrelation to the square of the hydroxyl ion concentration.

It is also known that developers with a relatively high concentration ofNa SO (50-100 grams/ 1000 ml.) are generally more stable to oxidationthan developers containing less sodium sulfite.

Even though it has not been possible to arrive at a general ruleexpressing the effectiveness of sodium arsenite in retarding oxidationin all developers it has been shown, however, that the addition of analkaline metal arsenite applied to a wide range of developer types hassubstantially increased in all instances the stability of thesedevelopers.

What is claimed is:

l. A photographic developer having increased stability against aerialoxidation which comprises an aqueous solution of organic developingagent, alkali metal sulfite, and a concentration of from about 1% toabout of alkali metal aresenite; said developer containing the alkalimetal arsenite in a concentration of from about 8% to about 10% whenformaldehyde is also present therein.

2. A high contrast, photographic developer suitable for photo-mechanicalwork and reversal processing of high contrast emulsions and havingincreased stability against aerial oxidation consisting essentially ofan aqueous solution of hydroquinone, 1-phenyl-3-pyrazolidone, alkalimetal carbonate, sodium sulfite, potassium bromide,

benzotriazole, sulfuric acid, and a concentration of from about 1% toabout 10% alkali metal arsenite.

3. A photographic developer for process photography having increasedstability against aerial oxidation consisting essentially of an aqueoussolution of hydroquinone, sodium sulfite, sodium carbonate, potassiumbromide, and a concentration of from about 1% to about 10% alkali metalarsenite.

4. An X-ray photographic developer having increased stability againstaerial oxidation consisting essentially of an aqueous solution ofmonomethyl para aminophenol sulfate, hydroquinone, sodium carbonate,potassium bromide, a concentration of more than 5% sodium sulfite, and aconcentration of from about 1% to about 10% alkali metal arsenite.

5. A photographic developer of the universal type having increasedstability against aerial oxidation consisting essentially of an aqueoussolution of monomethyl para aminophenol sulfate, hydroquinone, sodiumcarbonate, potassium bromide, a concentration of less than 5% sodiumsulfite, and a concentration of from about 1% to about 10% alkali metalarsenite.

6. A photographic litho-developer having increased stability againstaerial oxidation which comprises an aqueous solution of sodium sulfite,para-formaldehyde, sodium bisulfite, bonic acid, hydroquinone, potassiumbromide, and a concentration of from about 8% to about 10% alkali metalarsenite.

7. A photographic paper developer having increased stability againstaerial oxidation consisting essentially of an aqueous solution ofdiaminophenol di-hydro-chloride, sodium sulfite, potassium bromide, aconcentration of from about 1% to about 10% alkali metal arsenite, and abuffer to maintain the pH near 7.0.

8. A one-bath photographic developer-fixer having increased stabilityagainst aerial oxidation consisting essentially of an aqueous solutionof benzotriazole; potassium bromide; hydroquinone; sodium sulfite;sodium thiosulfate; a compound selected from the group consisting ofmonomethyl para aminophenol sulfate and 1-phenyl-3-pyrazolidone; acompound selected from the group consisting of alkali metal phosphate,alkali metal carbonate and alkali metal hydroxide; and a concentrationof from about 1% to about 10% alkali metal arsenite.

9. A photographic developer of the pyrosoda type having increasedstability against aerial oxidation consisting essentially of an aqueoussolution of sodium bisulfite, pyrogallol, potassium bromide, sodiumsulfite, sodium carbonate, and a concentration of from about 1% to about10% alkali metal arsenite.

References Cited in the file of this patent UNITED STATES PATENTS2,184,053 Muehler Dec. 19, 1939 2,845,349 Schwarz July 29, 19582,875,048 Haist et a1 Feb. 24, 1959

8. A ONE-BATH PHOTOGRAPHIC DEVELOPER-FIXER HAVING INCREASED STABILITYAGAINST AERIAL OXIDATION CONSISTING ESSENTIALLY OF AN AQUEOUS SOLUTIONOF BENZSOTRIAZOLE; POTASSIUM BROMIDE; HYDROQUINONE; SODIUM SULFITE;THIOSULFATE; A COMPOUND SELECTED FROM THE GROUP CONSISTING OF MONOMETHYLPARA AMINOPHENOL SULFATE AND 1-PHENYL-3-PYRAZOLIDONE; A COMPOUNDSELECTED FROM THE GROUP CONSISTING OF ALKALI METAL PHOSPAHTE, ALKALIMETAL CARBONATE AND ALKALI METAL HYDROXIDE; AND A CONCENTRATION OF FROMABOUT 1% TO ABOUT 10% ALKALI METAL ARSENITE.